Interference on 151.6625 or the input

[Medic Responder]

My fellow scanner buffs,

I am looking for some help solving an interference issue. My fire department is getting hammered by a distant station on 151.6625 & (the input) with a PL of 127.3. Judging by the propagation maps, we believe it is a station in Maine, and we have heard bits and pieces of traffic that sound like a towing company. The key to this is there are always DTMF tones when one of their radios keys up. If some of you in Maine could monitor those frequencies and let me know if you hear anything that could help identify the source, that would be greatly appreciated. From Mass, it is hard to make out any identifying info thru the static.


Thank you.

[W1MTW]

Doing a license search shows those 2 are owned by the same communications company, however, seperate systems. Both are located on Streaked Mountain. One question: Is it the same transmission on both frequencies?

[ecps92]

One thought, based on past experience, has anyone gone up to the Site and confirmed that No one left the repeater in CSQ mode for RX
which would make it heard any/all users/PL's but pass thru the output with the correct PL ??

Would not be the first or last time a Tech forgot to turn PL RX back on

My fellow scanner buffs,

I am looking for some help solving an interference issue. My fire department is getting hammered by a distant station on 151.6625 & (the input) with a PL of 127.3. Judging by the propagation maps, we believe it is a station in Maine, and we have heard bits and pieces of traffic that sound like a towing company. The key to this is there are always DTMF tones when one of their radios keys up. If some of you in Maine could monitor those frequencies and let me know if you hear anything that could help identify the source, that would be greatly appreciated. From Mass, it is hard to make out any identifying info thru the static.


Thank you.

[HigginsComm]

That could be users on the MaineStream solutions network. 151.6625 and (the frequency in question) would both be off Streaked Mountain and AAA is one of their customers. Streaked is a great tower site that covers a large area and has many different users. I would not be surprised that it could reach down to you in the right conditions.

Edit: I just replied to you as well on RR. I included the links to their FCC information there. I have attempted to contact Mainestream in the past with no avail and I have spoken with another radio shop who believes that MaineStream may no longer be in business.

[MrSvenSven]

VHF has a number of limitations that make it less than ideal. First, the entire public safety portion of the band is only 4MHz, so there isn't much to go around and there isn't much available. Apparently your department figured that out because your FCC license is actually a business license in the business portion of the band, not public safety.

The other problem is that the frequencies are 12.5KHz wide but spaced only 7.5KHz apart, so you overlap not only with other users on 1xx.x95, but also 1xx.x875 and 1xx.8025.

The biggest problem is that the frequencies aren't paired- that is, any frequency can be an input or an output. Your repeater is located on a hill listening on an input frequency while other agencies have repeaters on hills transmitting on that same frequency. There are other users who have base stations or repeater outputs licensed on (the frequency in question) including First Student in Milford NH and Belmont NH and the town of Chesterfield MA (who is at a very high site). It's likely that your repeater can hear one or all of these other users. If one of your users is talking when one of those other repeaters keys up, they might get covered up and become unreadable.

[W1MTW]

Would be interesting if MaineStream Solutions has folded. I knew one of their long time techs who was with them way back from the Active Communication days. If that's the case, who is maintaining their sites? RCM?

[HigginsComm]

I am not sure. I know Northeast Ambulance and LifeFlight is/was one of their clients, and they are not RCM's. I will do some digging tomorrow and see what I can find.

[W1MTW]

Which brings us back to the OP's issue. If this is a MaineStream site that's causing the issue, who's responsible? I go by the Falmouth site, and mostly see RCM trucks. Once in awhile, I see unmarked service trucks. Oh, MaineStream's website is no longer (you might already know).

[schwab]

That could be users on the MaineStream solutions network. 151.6625 and (the input in question) would both be off Streaked Mountain and AAA is one of their customers. Streaked is a great tower site that covers a large area and has many different users. I would not be surprised that it could reach down to you in the right conditions.

Edit: I just replied to you as well on RR. I included the links to their FCC information there. I have attempted to contact Mainestream in the past with no avail and I have spoken with another radio shop who believes that MaineStream may no longer be in business.

Well the OP stated they are hearing DTMF tones and and analog communications so that rules out MaineStream since that is an NXDN system.

[Medic Responder]

The emissions designator on these licenses is 11K2F3E.

[Medic Responder]

One thought, based on past experience, has anyone gone up to the Site and confirmed that No one left the repeater in CSQ mode for RX
which would make it heard any/all users/PL's but pass thru the output with the correct PL ??

Would not be the first or last time a Tech forgot to turn PL RX back on

I had the same thought. I just tried transmitting on (the input) in CSQ mode, and I didn't trip our repeater, so I don't think our receiver is set to CSQ.

[HigginsComm]

MaineStream has both an analog network and an IDAS network. It was originally installed with Icom as the primary supplier. Also, the IDAS network is on different frequencies than those posted. The listed frequencies are MaineStream's analog system.

According to my sources, MaineStream as a business no longer exists, however they have a tech who is honoring their customers. I have also been told that most of their customers that have left the system have gone to a Motorola dealer running a statewide DMR / analog mixed system. I was told it is NOT RCM.

My suggestion to the OP at this point would be to have your licensee (Deputy Chief Fisher) reach out to your licensing agent (Wright / Green Mountain Communications in Pembroke, NH) and have them start digging. Knowing that tower site, I have received and transmitted to it from as far south as the Mass state line and as north as the Canadian border, so it would not be surprising if they are who you are dealing with.

[Medic Responder]

Thank you Steve, I appreciate your help. It would be nice to not have the overnight crew have to chose between listening to static all night or turning off the radio and possibly missing a call

[ecps92]

Rules that out.

Also, keep in mind (Again just a WAG) it could be +/- the actual freq too and I would not rule out (based on Elevations) any of the New England state or Canada as the source

Also any audio to review of the interference ?
might provide a (if a towing Co) Rte/Hwy number ?

[Medic Responder]

Last fall (we deal with this every fall), during one clear transmission, I heard I-95 mentioned. Also, I stayed up until 3am one morning when the propagation was especially strong, and I was only hearing one side of the conversation, which would make sense if it is an LTR system. The recordings have too much static to make anything out, it is a bit easier to hear thru the static on the actual radio. The only constant clue is the DTMF tones when a user keys up. Which is why I was asking if any monitors up in Maine could sit on the 159 frequency and listen for anything that might point us in the right direction.

[W1KNE]

Last fall (we deal with this every fall), during one clear transmission, I heard I-95 mentioned. Also, I stayed up until 3am one morning when the propagation was especially strong, and I was only hearing one side of the conversation, which would make sense if it is an LTR system. The recordings have too much static to make anything out, it is a bit easier to hear thru the static on the actual radio. The only constant clue is the DTMF tones when a user keys up. Which is why I was asking if any monitors up in Maine could sit on the 159 frequency and listen for anything that might point us in the right direction.

If you were only hearing one side, that wouldn't be a LTR system. You'd hear the data on the frequency that sounds like an open dead carrier if it was LTR. You're hearing a straight forward conventional base station.

Which frequency are you hearing it on?
.6625 or the input?

This information you just provided may help to narrow it down.

[Medic Responder]

I believe it is coming thru (the input) which is being retransmitted via our output on .6625. Everything we are hearing is coming thru our repeater. We are not hearing the interfering station's repeater directly; we only hear it being retransmitted via our repeater.

[MrSvenSven]

I believe it is coming thru (the input) which is being retransmitted via our output on .6625. Everything we are hearing is coming thru our repeater. We are not hearing the interfering station's repeater directly; we only hear it being retransmitted via our repeater.

You are describing the most likely scenario, which means that 151.6625 isn't your problem and you can focus on the input.

As I mentioned in my first post, this is just one of the inherent problems with VHF. Even if you do identify the interferer, what are you going to do about it? Your easiest and quickest solution is probably to change the PL tone that you use on your input frequency and reprogram all your radios for the new tone. You don't need to identify the interfering station to do that.

If you have the budget for frequency coordination and a retune of your repeater's duplexer, I would suggest you look into switching to a repeater input frequency in the public safety portion of the band.

[W1KNE]

Even if you do identify the interferer, what are you going to do about it?

Your easiest and quickest solution is probably to change the PL tone that you use on your input frequency and reprogram all your radios for the new tone. You don't need to identify the interfering station to do that.

The only leverage he will have if he identifies it, is if it happens to be someone operating without a license, then he can contact the Enforcement Bureau. But other than that, you're correct in the assessment that the best fix is to just change the input PL tone and move on. Gardner, MA and Woonsocket, RI had to do this with their repeaters several years back for this exact reason.

[ChrisP]

I think I found the answer. (The frequency in question) is the input to the public safety repeater used at the Fryeburg Fair in Maine (the output being 153.2525). They use a CTCSS tone of 127.3, and there are almost always DTMF tones used when the repeater is keyed up. I can personally confirm all of the above from just last weekend.

Here is the license: Conventional License - WQLC681 - REILLY, JOHN C
https://wireless2.fcc.gov/UlsApp/UlsSea ... ndow=false
Specifically noted in the license: 90.35a - RADIOS WILL BE USED FOR COMMUNICATIONS AT FAIRS AND FESTIVALS

I don't know if/how much that repeater is used when the fair isn't in session (or if it's even removed to be used elsewhere), but it'll be interesting to see if your interference stops now that the fair is over.

[Medic Responder]

Interesting! Thank you! We did not hear anything yesterday when propagation was very strong. I heard Norway ME Fire booming in on the Essex County MA Fire mutual aid frequency, and I was surprised that we didn't receive any interference on our frequency. This could be why. I'll have to get the dates of the Fryeburg Fair in advance of next year and see if we can correlate its use with the interference. Thanks again.

[W1KNE]

Interesting! Thank you! We did not hear anything yesterday when propagation was very strong. I heard Norway ME Fire booming in on the Essex County MA Fire mutual aid frequency, and I was surprised that we didn't receive any interference on our frequency. This could be why. I'll have to get the dates of the Fryeburg Fair in advance of next year and see if we can correlate its use with the interference. Thanks again.

Hi Gabriel

I am glad we were able to help. Good luck hoping to track it down. FYI for you and everyone, we've had a very long standing policy of not publishing input frequencies to public safety systems. Both here and in the wiki.
Due to the nature of this thread, I had allowed it until you found the source. Now that you have a solid clue into it, I've gone ahead and removed all references to your input frequency. I think the idea suggested by ChrisP is legitimate.

Please do not repost the frequency in the future. It can be found out easy enough. If you end up resolving this, or IDing it, please let us know.

-- Mike

[Medic Responder]

Thank you, Mike. I appreciate everyone's help with this.